Spongy (gypsy) moth egg masses are the best indicator of population size and health for the coming season.  If we know the density of the egg masses, their average size, and the amount of parasitism on the eggs, we can predict with a high degree of accuracy what the coming summer's population will likely be in that area.

The egg mass surveys are conducted throughout the County in the fall and early winter.  This information determines where the spray is needed and where it is not.  Populations have become very patchy in recent years, making the surveys even more important in guiding the spray.

The adult female spongy (gypsy) moth lays the egg mass soon after emerging from the pupae in late July or August.  She then dies without feeding and the eggs stay on the tree until hatching next spring.  When new, the egg masses are generally a rich tan or brown color with a smooth exterior.  As they age over winter, they become bleached to a light tan and the exterior becomes eroded and weathered.